Asian Hornets in the UK: What You Need to Know About the Yellow-Legged Hornet

The Asian hornet, also known as the yellow-legged hornet, has become a growing concern across Europe and is closely monitored in the UK. While sightings remain relatively rare compared to common wasps and native hornets, this invasive species poses a significant threat to honey bees and other pollinating insects.

Understanding how to identify Asian hornets, where they are found, and what to do if you spot one can help protect the UK's biodiversity and support ongoing efforts to prevent their establishment.

What Is an Asian Hornet?

The Asian hornet (Vespa velutina nigrithorax), often called the yellow-legged hornet, is a species native to Southeast Asia. It was accidentally introduced into Europe in the early 2000s and has since spread through several countries, including France, Spain, Belgium, and parts of the Netherlands.

The species was first detected in the UK in 2016, and authorities continue to monitor and eradicate nests whenever they are discovered.

Why Are Asian Hornets a Concern?

Unlike native hornets, Asian hornets are highly efficient predators of honey bees.

Worker hornets often hover outside beehives, catching returning bees in flight before carrying them back to the nest to feed developing larvae.

A single colony can consume large numbers of pollinating insects throughout the season, including:

• Honey bees
• Bumblebees
• Solitary bees
• Wasps
• Flies and other insects

For beekeepers, a sustained Asian hornet presence can place considerable pressure on local bee colonies.

How to Identify an Asian Hornet

Accurate identification is important because Asian hornets are frequently confused with the native European hornet.

Key Features of an Asian Hornet

• Dark brown or almost black body
• Velvety dark thorax
• Thin yellow band near the rear of the abdomen
• Distinctive orange fourth abdominal segment
• Bright yellow leg tips
• Approximately 20–30 mm in length

The yellow legs are one of the easiest identification features and are responsible for the common name "yellow-legged hornet."

How They Differ From European Hornets

The UK's native European hornet is generally:

• Larger than an Asian hornet
• More reddish-brown in colour
• More yellow across the abdomen
• Less uniformly dark

Many reported Asian hornet sightings turn out to be European hornets or other harmless insects.

Where Do Asian Hornets Build Nests?

Asian hornets typically construct two nests during their annual lifecycle.

Primary Nest

In spring, the queen begins a small starter nest in sheltered locations such as:

• Sheds
• Garages
• Roof spaces
• Outbuildings
• Dense vegetation
  

Secondary Nest

As the colony grows, a much larger secondary nest is often built high in trees.

These nests can be:

• More than a metre in diameter
• Located over 10 metres above ground
• Home to thousands of hornets

Because of their height and concealment, many nests remain unnoticed until autumn.

The Asian Hornet Life Cycle

Like wasps and native hornets, Asian hornets follow an annual colony cycle.

Spring

• Queens emerge from winter hibernation.
• New nests are established.
• Eggs are laid.

Early Summer

• Worker hornets emerge.
• Colony growth accelerates.
• Nest expansion continues.

Late Summer

• Colonies reach peak population.
• Predation on bees increases significantly.
• New queens and males are produced.

Autumn

• Mating occurs.
• Fertilised queens seek winter shelter.
• The original colony dies out.

Only newly fertilised queens survive to begin the next generation.

Are Asian Hornets Dangerous to People?

Asian hornets are not generally aggressive when away from their nest.

However, they can become defensive if a nest is disturbed.

Like wasps and native hornets, they can sting multiple times. Most stings result in temporary pain and swelling, but severe allergic reactions can occur in sensitive individuals.

The greatest concern associated with Asian hornets is their impact on pollinators rather than an increased threat to the general public.

What Should You Do If You See One?

If you believe you have seen an Asian hornet:

• Remain at a safe distance.
• Take a clear photograph if possible.
• Note the location.
• Avoid disturbing the insect or any potential nest.
• Report the sighting through the appropriate UK reporting channels.

Photographs are extremely valuable because many suspected sightings are ultimately identified as native insects

How to report an Asian / Yellow Legged Hornet

​Common Insects Mistaken for Asian Hornets

Several UK insects are regularly confused with Asian hornets, including:

• European hornets
• Common wasps
• Hornet mimic hoverflies
• Giant wood wasps
• Certain species of large flies

Careful identification helps ensure resources are focused on genuine sightings.

Preventing the Spread of Asian Hornets

The UK's surveillance and rapid response programmes have helped prevent the widespread establishment of Asian hornets.

Members of the public play an important role by:

• Learning how to identify the species
• Reporting suspected sightings
• Remaining vigilant during spring and summer
• Supporting local beekeeping and pollinator conservation efforts

Early detection remains one of the most effective ways to prevent the species from becoming permanently established.

Final Thoughts

The Asian hornet, or yellow-legged hornet, is one of the most closely monitored invasive insects in the UK. Although sightings remain relatively uncommon, their potential impact on honey bees and other pollinators makes public awareness essential.

By learning how to recognise this species and reporting suspected sightings, homeowners, gardeners, and beekeepers can all contribute to protecting the UK's valuable pollinator populations and supporting ongoing conservation efforts.